Eductor system for water ring vacuum pump

ABSTRACT

There is disclosed an improved vacuum assembly for forming a vacuum comprising a vacuum pump having water rings wherein a water stream is injected into the water rings of the vacuum pump and wherein the water stream is comprised of a combined fresh water and a recycled waste water stream and wherein the fresh water stream is used as a motivating force for an eductor for inducing the recycled waste water stream to form the water stream injected into the water rings of the vacuum pump.

This is a division of application Ser. No. 07/287,987, filed Dec. 20,1988 now U.S. Pat. No. 4,919,826.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to an improved process and apparatus for treatinga gas-liquid-solid effluent stream, and more particularly to an improvedprocess and apparatus for separating into component streams agas-liquid-solids effluent stream resulting from dental procedures.

(2) Description of the Prior Art

A typical dental effluent stream, i.e. from an oral vacuum tube in adental application contains water, air and other gases, such as nitrousoxide; lighter than water particles, such as human tissue and heavierthan water particles, such as ground tooth particles, filling, etc. Mostof such particles, and in particular the larger ones, are separated by ascreen and filter bowl assembly at the inlet of a pump, such as a waterring vacuum pump. The smaller particles, water, liquids and gases aredrawn into the suction side of the vacuum pump and thereafter dischargedfrom the pump. The effluent liquid and gases may be dumped into a venteddrain, or as is more prevalent, primarily because of environment codes,are introduced into an air-water separator to separate liquid from gas,dumping the liquid and smaller suspended lighter and heavier than waterparticles through a trap into a drain and venting to atmosphere thegases via a separate line. The separation of gas-liquid mixtures is notvery effective in present dental applications, and significant liquidincluding contaminants suspended and dissolved in the liquid may becarried away in the vent stream.

Vacuum evacuation systems, for example, used in some dental or processapplications, include vacuum pump assemblies having water rings as theprime mover for creation of vacuum. Such pumps must continuously besupplied with water to lubricate and cool internal seals and provide the"piston" action to alternately draw in and expel the liquid-gas mixturedesigned to be handled by the water rings of such system.

Additionally, and primarily because of environmental, specifically waterconservation, reasons, but also for economic and financial reasons, suchwater based evacuation systems have recently been equipped with waterconservation subsystems, commonly referred to as "water recyclers" or"water recirculators". The useful effect, that of recirculating water insuch conservation subsystems, is carried out by extracting from thedischarged effluent water stream a portion of that waste water flow andre-introducing this portion of recirculated water into the vacuum pumpalong with a reduced amount of fresh water flow. The net savings offresh water is the difference between the water consumption withoutrecirculation and that with recirculation. The recirculated water addedto the reduced fresh water flow may or may not add up to an amount equalto 100% of the flow normally introduced into the pump when operatingwithout recirculation.

It is assumed that the state of the art and general operation of thewater pump is well understood. However, it is important to emphasize theeffects of certain parameters on pump performance. Theseeffects/parameters include, but are not limited to, the following, inorder of strongest dependence wherein pump's operating efficiently is afunction of:

1. the pump supply water temperature;

2. the total quantity of water introduced into the pump;

3. the location in the pump where water is introduced; and

4. the cleanliness of the supply water.

Reasons for such importance, and the explanations for these behaviorsare:

1. For a given water inflow rate, a pump can handle a certain volumetricrate of gases. With increasing temperature the vapor pressure of waterincreases thereby increasing the proportion of water vapor contained inthe gas mixture which the pump has to move. Therefore, the volume ofgases other than water vapor, namely those entering a dentist'shandpiece and/or saliva ejector, and which is the volume of gasesdesired to be moved by the pump, decreases.

2. At a given water temperature, the performance of the pump increaseswith increasing quantity of water up to some maximum performance for aspecific value of water inflow rate. Above that specific water inflowrate, the pump's performance decreases. This is due to the fact thatinitially, with small water injection rates, a circular ring of water isbuilt up within a cylindrical cavity and the eccentrically mountedimpeller outer radius is only partially immersed in the "water ring". Asa greater water rate is added, this outer water ring increases inthickness until the impeller outer radius is continuously in contactwith the ring of water. It is for this water ring thickness and thecorresponding water injection rate that the pump has maximumperformance. By injecting more water, the water ring thickens and thegas moving cavities in the impeller decrease in volume, thereby reducingthe volumetric rate of gases that can be moved by the pump.

3. Some water ring pumps introduce the water through the intakemanifold, others through special water injection ports built into thepump housing and others use a combination of both. The best performancecan be achieved by introducing all of the water through the specialinjection ports in the housing. This is because bringing the water inthrough the intake manifold reduces the volume of gas that can occupythe inflow area, and increase the drag on the gases desired to be moved,because the added water must be accelerated by the gas flow. Also, thewater in the inlet manifold is broken into droplets, increasing thesurface area of the water allowing more water to vaporize therebydecreasing the volume of other gases and ergo decreasing the performanceof the pump. This situation is exacerbated during the recirculation ofwater, because recirculated water is by its very nature warmer, and so acompound degradation of performance results.

4. The cleaner the supply water is, the longer the pump will last andthe better it will operate. Dirty injection water will cause abrasion ofsome pump and ducting parts and coating with biological material onothers. Abrasion wears parts, thereby increasing critical tolerancesbetween moving parts which decreases performance. Coating of other partsreduces the volumes and areas which increase flow resistance anddecrease flow rates, thereby decreased performance. It is thereforeimportant to extract recirculated water in as clean a state as possible.

In existing water recycling systems, the location of recirculated waterextraction is typically within a standard sized or an enlarged versionof a common plumbing trap of the drainage stream below an "air-water"separator, regardless of the simplicity or sophistication of such anair-water separator. ("Air" in this context refers to any and all gasesin the effluent stream including water vapor.) Such traps contain highlyagitated and mixed water flows, and in some applications can easily be"blown out" because of an inefficient upstream air water separator. Thisprovides dirty and at times no recirculation flow, but only gas. Thissometimes non-existent or otherwise dirty water is typically introducedinto some portion of the intake manifold of the vacuum pump.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an improved process andapparatus for separating into component streams a combinedgas-solid-liquid effluent.

Another object of the present invention is to provide an improvedprocess and apparatus for separating into component streams a combinedgas-solid-liquid effluent obtained during dental procedure.

Still another object of the present invention is to provide an improvedprocess and apparatus for separating into component streams a combinedgas-solid-liquid effluent for recovery of a water stream permitting ofits reuse.

A further object of the present invention is to provide an improvedprocess and apparatus for separating into component streams a combinedgas-solid-liquid effluent for recovery of a water stream for reuse fromwhich some heavier than liquid particles and some lighter than liquidparticles have been removed.

A still further object of the present invention is to provide animproved process and apparatus for separating which provides effluentlow level drain for heavier than liquid particles.

Yet another object of the present invention is to provide an improvedprocess and apparatus which allows extraction of relatively cleanerwater for another process, and a high level overflow drain for lighterthan liquid particles and the balance of liquid to be discharged toanother process or waste.

Still another object of the present invention is to provide an improvedprocess and apparatus which allows the centrifugal/gravity separation asan amalgam extractor.

SUMMARY OF THE INVENTION

These and other objects of the present invention are achieved in animproved liquid-solids-gas separator assembly achieved by an improvedvacuum assembly for forming a vacuum comprising a vacuum pump havingwater rings wherein a water stream is injected into the water rings ofthe vacuum pump and wherein the water stream is comprised of a combinedfresh water and a recycled waste water stream and wherein the freshwater stream is used as a motivating force for an eductor for inducingthe recycled waste water stream to form the water stream injected intothe water rings of the vacuum pump.

BRIEF DESCRIPTION OF THE DRAWING

Further objects and advantages of the present invention will becomeapparent upon consideration of the detailed disclosure thereof,especially when taken with the accompanying drawings wherein;

FIG. 1 is a cross-sectional elevational view of the separator assembly;

FIG. 2 is a cross-sectional view taken along the lines II--II of FIG. 1;and

FIG. 3 is a partial schematic flow diagram of a vacuum pump assemblyincluding separator assembly of FIG. 1 and eductor-check valve withby-pass loop assembly.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and in particular FIGS. 1 and 2, there isillustrated a separator assembly, generally indicated as 10 comprised ofa generally cylindrically-shaped outer wall 12, a conically-shaped topwall 14, a conically-shaped bottom wall 16 and a conically-shapedintermediate wall member 18 including an opening 20 defining an upperseparation chamber 22. The top wall 14 is formed with avertically-disposed conduit member 26 extending therethrough and intothe chamber 22 defining a gas-liquid separation zone 28 defined by aninner surface portion 30 of the top wall 14 with an outercylindrically-shaped surface portion 32 of the conduit member 26.Extension of the conduit member 26 defined by the surface portion 32 maybe omitted depending on the proportions and relationships of surfacesand dimensions of the separator assembly 10.

In a mid portion of the outer wall 12, there is provided ahorizontally-disposed inlet conduit member 34 leading to an opening 36in the outer wall 12. A portion 38 of the outer wall 12, referring toFIG. 2, extends beyond an end portion 40 of the conduit member 34 todirect fluid flow against interior surface portion 42 of the conduitmember 34 and inner surface of the outer wall 12 thereby to enhanceliquid contact with such interior surface and concomitant gas-liquidseparation about such surface portion 42. The frusto-conically-shapedintermediate wall member 18 extends inwardly and downwardly from theouter wall 12. The intermediate wall member 18 is generally parallellydisposed with respect to the bottom wall 16 defining aliquid-liquid-solids lower separation chamber 24. The bottom wall member16 is formed with a centrally-disposed opening 43 in communication via achannel 44 with a lower vertically-disposed conduit 46 to allow apredetermined amount of liquid and the heavier than liquid particles todrain through the channel 44.

Extending upwardly into the lower separation chamber 24, there areprovided a vertically-disposed first conduit member 48 having an upperopening 50 and a second vertically-disposed conduit member 52 having anupper opening 54. The opening 50 and 54 of the first and second conduitmembers 48 and 52, respectively, are positioned below the intermediatewall member 18 and outside a horizontal area defined by the opening 20,as more fully hereinafter described. It is also the function of member18 to act as a baffle and fluid diverter to prevent fluid borne debrisfrom droping directly into the openings 50 and 54 upon entering chamber24.

The opening 50 of the first conduit member 48 is disposed in ahorizontal plane above the opening 54 of the second conduit member 52with the opening 50 of the first conduit member 48 functioning as a weirfor overflow of liquids and lighter than liquid particles and theopening 54 of the second conduit member 52 functioning to allowextraction of liquids from which significantly heavier and lighter thanliquid particles have been removed. The conduit member 48 is in fluidcommunication via an opening 56 with the lower conduit member 46 whichis in fluid flow communication by line 58 through a plumbing trap 60 toa disposal system (not shown). Alternately, conduits 48 and 46 may beconfigured to not join at opening 56, thereby allowing liquid withpredominantly lighter than water particles and liquid with predominantlyheavier than liquid particles to be drained separately. Such separatedraining, for example could enhance the separation of small amalgamparticles from the disposal system.

The second conduit member 52 is in fluid flow communication by line 64under the control of valve 66 with the vacuum pump assembly, as morefully hereinafter described. Vertically-disposed and extendingdownwardly through the opening 43, there is provided an agitating wiremember 68 mounted (not shown) for lateral and/or rotational movementwithin the channel 44 to prevent solids build-up about the opening 43and within channel 44. The conduit member 26 is in gaseous communicationin the direction of line 70 with the atmosphere.

The separator assembly 10 of the present invention is included inanother aspect of the present invention to provide a portion of thewater requirement for the water rings of the prime mover of a vacuumpump assembly for creation of vacuum, generally indicated as 80,referring now to FIG. 3. The vacuum pump assembly 80 is comprised of avacuum pump 82 including an inlet conduit 84 and an outlet conduit 86,pump motor 88 and an electrical box 90. The vacuum pump 82 is providedwith a water supply line 92 in fluid flow communication with water rings94 and the housing chamber 96 of the vacuum pump 82 as more fullyhereinafter described. The inlet conduit 84 of the vacuum pump 82 is influid flow communication with a solid filter assembly 98 which is influid flow communication by line 100 with a vacuum valve assembly,generally indicated as 102, such as described in copending U.S.application Ser. No. 193,769, filed May 13, 1988, assigned to the sameassignee as the present invention and incorporate herein by reference.The outlet conduit 86 of the vacuum pump 82 is connected by line 104 tothe inlet conduit member 34 of the separator assembly 10.

The water supply line 92 is in fluid flow communication with an eductorassembly, generally indicated as 106, with a source of fresh water inline 92 and recirculated water in line 64 as more fully hereinafterdescribed. The eductor assembly 106 includes an eductor housing 110having a fresh water inlet conduit 112, a recirculation inlet conduit114 and an outlet conduit 116 and is provided with a nozzle 118 and aventuri device 120. The outlet conduit 116 of the eductor assembly 106is in fluid flow communication via line 122 under the control of threeway valve (or tee and check valve) 124 with the water supply line 92 forthe vacuum pump assembly 80. The three way valve 124 is in fluid flowcommunication by line 126 with the three-way valve 128 as more fullyhereinafter described.

The fresh water supply line 108 is in fluid flow communication with thefresh water inlet conduit 112 of the eductor assembly 106 via a strainer130, a valve assembly 132 under the control of a solenoid (not shown)operated by the electric control assembly 90, one way valve 134, a flowrestrictor 136 and thence through three-way valve 128 via line 138 underthe control of pressure regulator 140.

In operation referring to FIG. 3, a vacuum stream in line 100 from thevacuum valve assembly 102 including liquids, water, water vapor, gaseouscomponents and solid particulate material including tooth particles,filling materials, decay, etc. is passed by line 100 through the solidsfilter unit 98 and thence by line 84 to the suction side or inlet of thevacuum pump 82. In the solids filter assembly 98, particulate materialhaving a particular size of greater than about 400μ are separated fromthe stream prior to inhalation of a resulting gas-liquid-solid mixturein line 84 into the vacuum pump 82. Water introduced by line 92 to thewater rings 94 and into the chamber 96 is combined with the mixture andpassed by line 104 from outlet conduit 86 of the vacuum pump 82 into theseparator assembly 10 for processing as more fully hereinafterdescribed, to provide a recirculation water stream in line 64. Theliquid stream in line 64 from the separator assembly 10 is passed to theinlet conduit 114 of the eductor assembly 106.

The water requirements for the vacuum pump assembly 82 are provided byfresh water in line 108 and the recirculation water in line 64 with thepressure of the fresh water stream in line 138 providing the means forforming the water stream in line 92 introduced into the vacuum pump 82.The pressure of the fresh water stream in line 108 is generally of fromabout 30 to about 100 psig. regulated to 30 psig. by pressure regulator140 and under the control of valve 132 in response to an on-modecondition of the motor 88 is passed through the strainer 130 to removeany particulate material of a particulate size greater than 200μ, and isthence passed through the flow restrictor 136 to control waterflow rate,generally 0.5 to 0.75 gpm. depending on pump size prior to introductioninto the eductor assembly 106 for passage through the nozzle 118 toentrain recirculating water in line 64 introduced by conduit 114 andform a combined water stream in line 122 after passage through theventuri 120, which is preferably of like pressure and of a like quantityof a fresh water stream, per se, which would be necessary to operate thevacuum pump assembly 82 by passage thereto by line 126 under the controlvalves 128 and 124 and thence through line 92 in the absence of suchrecirculation water stream, sometimes referred to as the by-pass path.

In such manner, fresh water requirements for the vacuum pump 82 aresubstantially reduced, e.g. of from 25 to 40 percent of usual freshwater requirements, and thus provides a correponding savings of from 75to 60 percent of fresh water as well as concomitantly reducing dischargerequirements of an untreated effluent stream withdrawn from thedischarge side of the vacuum pump 82. The amount of recirculated waterflow will vary slightly depending on operating condition of the systemat any given time, but is always sufficient to provide for properoperation of the vacuum pump 82. Generally, fresh water supply is arelatively fixed value depending primarily on the pressure of the freshwater supply and the nozzle orifice size. Should the eductor assembly106 become inoperative, the fresh water requirements for the vacuum pumpassembly 82 in line 92 may be supplied from the fresh water supply line108 via line 126 under the control of by-pass valves 128 and 124.

It has been found that the pump performance, as measured and judged byboth the volume flow rate of ingested gases, such as air at a givenvacuum pressure and the highest vacuum pressure attainable, is afunction of both the amount of liquid and the temperature of the liquidentering the pump. There is an optimum liquid rate below and above whichthe performance of a liquid ring pump deteriorates and as the liquidtemperature increases the performances decreases, the latter being thestronger influence. Increasing the liquid rate also increases the loadon the pump and hence the power requirement. Increasing the temperatureof the liquid into the pump decreases the performance of the pump due tothe increased vapor pressure of the liquid.

Recirculated liquid has an increased temperature, therefore, mixingrecirculated liquid with fresh liquid increases the temperature of thepump supply liquid correspondingly. Based on liquid supply flow rateonly, it would seem that the recirculated fluid plus fresh fluid shouldtotal the design flow rate for maximum performance. However, because ofthe stronger dependence of performance on liquid temperature, it isdesirable to entrain less than the full amount of recirculated liquidfor optimal recirculation performance, which because of temperaturereasons is always less than total fresh water injection performance. Inany case, the fresh water supply rate in the recycling mode of thismanifestation is independent of and unaffected by the variation ofrecirculated water flow rate, being determined by the regulated liquidsupply pressure and the diameter of the nozzle opening in the eductorhereinafter described.

The gas-liquid-solid effluent stream withdrawn from the outlet conduit86 of the vacuum pump 82 is passed by line 104 to the inlet conduitmember 34 of the separator assembly 10, referring now to FIG. 1. Theeffluent stream is tangentially introduced into the chamber 22 of theseparator assembly 10 along inner surface of the wall 12 thereof atforce sufficient to permit gas-liquid separation with eventual gasremoval via conduit 26 and vented via line 70 to the atmosphere. Toinsure gas separation from the liquid and solids, the separator assembly10 is formed with the gas-liquid separation zone 28 whereby any liquidand entrained solids rising up the surface of the wall 12 contacts theouter surface 32 of the conduit member 26 for gravity flow downwardlyalong the outer surface 32 through the upper chamber 22 into theliquid-solids collection and separator chamber 24. The liquid andentrained solids flow downwardly through the opening 20 in theintermediate plate member 18 and thence into the separator andcollection chamber 24 with solids build-up about the base portion of thebottom wall member 16.

In the lower separation chamber 24, the liquid phase is collected underconditions establishing a liquid level (L) as determined by the heightof the opening 50 with lighter than liquid particles and lighter liquidspermitted to overflow the opening 50 and flow down the conduit 48 to beadmixed in conduit 46 with heavier than liquid particulate matter andheavier liquids passing through the channel 44. The agitating member 68is freely disposed through the orifice 43 and into the channel 44 tominimize solids build-up. The liquid flow rate through orifice 43 andchannel 44 is fixed by the diameter of orifice 43 thereby establishingthe diameter of agitating member 68 and the head of liquid to the levelof opening 50, as understood by one skilled in the art. The combinedliquid-solids stream in conduit 46 is withdrawn by line 58 and passed towaste discharge.

By keeping conduits 48 and 46 separate, it is possible to separatelydischarge lighter and heavier than liquid particles. Intermediatedensity liquids, primarily water, is withdrawn through the opening 54and passed by conduit member 52 to line 64 under the control of valve 66as the recirculation water stream to be passed to the inlet conduit 114of the eductor assembly 104 as hereinabove discussed.

It is well known that the total energy of a system consists of the sumof kinetic energy, potential energy and thermal energy. In a gas stream,by comparison, the potential energy is negligible and can therefore beignored. If a gas stream contains kinetic energy of motion and thismotion is abruptly and turbulently brought to a significantly smallervelocity, the organized kinetic energy of the gas stream is convertedinto thermal energy primarily through frictional effects. If anotherfluid, such as a liquid is intermixed with the gas, this thermal energyis absorbed by the liquid thus raising its temperature. If, on the otherhand the liquid is significantly separated from the gas prior to anyfrictional deceleration, and such deceleration is minimized by properaerodynamic design, a significant amount of kinetic energy can betransported to be lost in a region remote from where the liquid canabsorb that converted heat, then the separated water would have atemperature below that of the abrupt and turbulent decelerationpreviously described.

The present invention possesses the characteristics of heat dissipation,such that heat is transported away by a highly vortical exiting airstream where the heat is dissipated in the gas vent instead of beingtransmitted to the fluid within the gas-liquid separation chamber. Thisis achieved by means of the tangential and smooth surface junctions ofsurfaces, the introduction of fluids into the separation chamber in asmooth, tangential manner via a slowly varying cross sectional areainlet and the imparting to the gas a high vortical or angular velocity.

The concomitant centrifugal and centripetal forces created by theconfiguration design separate the fluid very quickly from the gas, thendraining peripherally under the action of gravity to expose minimalsurface area to the gas for absorption of thermal energy. The turbulentdischarge cited as an example of the prior art contains many dropletswhich in total have a very large surface area and are in the abruptlyslowed warmed gas flow, therefore providing an enhanced liquid warmingenvironment. Although this effect is not a major thermal load, itnevertheless underscores another advantage of the embodiment of thisinvention.

EXAMPLE OF THE INVENTION

Operation of the process and apparatus of the present invention isdescribed in the following example which is intended to be merelyillustrative and the invention is not to be regarded as limited thereto.

EXAMPLE

A nominally rated 1.0 horsepower motor drives a water ring vacuum pumpcapable of evacuating about 900 standard cubic feet per minute of air(and/or gas mixture) at a vacuum pressure of about 5 inches of mercury(and about 700 scfm at about 9 inches of mercury) requiring about onehalf gallon per minute of water for optimum performance. The eductor isconstructed with a nozzle diameter to deliver water with a flow rate of25% of 1/2 gpm or about 1/8 gpm and consistent with a regulated freshwater supply pressure of about 30 psig. Low pressure recirculated wateris entrained by the fresh water in the eductor for delivery at theintermediate pressure into the regular injection ports of the pumphousing. The clean water separator extracts a portion of the 400μ debrisfrom the recirculated water thereby reducing the total amount of debriswhich is reintroduced into the vacuum pump, as compared to systems ofthe prior art. Recirculation in accordance with the present embodimentreduces pump performance by only between 2% and 8 % depending on thevacuum and suction flow rate, as compared to the recirculation methodsof the prior art which exhibit reductions of from 4% to 16% for similarrecirculation water temperature and flow rate. Reducing the amount offresh water into the pump and recirculating a portion of the totalamount of water required by the pump for optional operation also reducesthe amount of water discharged as actual waste stream.

Thus, in accordance with the present invention, there is a significantreduction in quantity of a waste stream to enter the local disposaltreatment plants. Additionally, there is a significant reduction infresh water requirements providing economic benefits through reducedfresh water consumption. The system permits facile operation withminimum requirements for operator maintenance and control as well asproviding for emergency override fluid by-pass to minimize potentialdamage and/or downtime to the vacuum pump assembly.

While the present invention has been described with reference tocylindrical and circular shapes, and it is obvious to one skilled in theart that spiral and elliptically shaped surfaces and shapes such asfrustum conical surfaces create equivalent boundaries for providingcentripetal forces for liquid separation from gases and heavier thanliquid particles from liquids. It is also recognized that the aspectratio of diameter to height of various components can be varied withinthe context of these separation phenomena. Furthermore it is essentialto recognize that the conical member 18 whether implemented as shown inFIG. 1, or inverted as alternately described herein earlier, performsthe same function of baffling and in the limit could be a flat disk withsuitable perforations. The importance of this baffle member is that itacts as a baffle serving both to direct liquid and shield the drainageopenings as well as to separate the turbulent and agitated gasflow fromthe smoother desired liquid discharge flow.

In addition, should a recycling liquid system not be required, thegas-liquid separation device pictured in FIG. 1 can be used strictly asa gas-liquid separator in such a manner that all drainage paths arecombined to form one leading into a common plumbing trap for liquiddischarge. A simplification of the discharge channels is then possibleby eliminating conduits 52 and 48, enlarging orifice 42 and thus duct44, and eliminating the agitation device 68. The baffle 18 is then anoptional component and is not required, except to reduce internalsplashing.

The curved inlet duct 34 can also be shaped in such a fashion that thecross sectional flow area increases gradually and smoothly to allowsmooth deceleration of the pump discharge flow while simultaneouslybeing curved to provide simultaneous centrifugal separation of theliquid from the gases. Smooth deceleration of the incoming stream allowsgravity to contribute to the separation process early on.

The benefits accrued in this embodiment are:

1. a defined and specific reduction in fresh water consumption, 75% inthis example;

2. a defined and specific reduction of liquid subject to disposal intothe environment, 75% in this example;

3. reduction of debris particulates recirculated through the pump;

4. injection of recirculated and fresh water directly into the pumphousing water injection ports;

5. optimization of recirculated water quantity to minimize reduction ofperformance due to water temperature rise;

6. internal aerodynamic design to preclude blowing out of traps, and tominimize the expulsion of water droplets with the separated air stream.

While the invention has been described in connection with an exemplaryembodiment thereof, it will be understood that many modifications willbe apparent to those of ordinary skill in the art; and that thisapplication is intended to cover any adaptations of variations thereof.Therefore, it is manifestly intended that this invention be only limitedby the claims and equivalents thereof.

What is claimed:
 1. A vacuum assembly for forming a vacuum stream, whichcomprises:a vacuum pump including water rings; conduit means forinjecting a water stream into said water rings of said vacuum pump; aseparation apparatus means for separating gas from liquid; conduit meansfor withdrawing a liquid-gas stream from said vacuum pump and passingsaid liquid-gas stream to said separation apparatus means; conduit meansfor withdrawing a recirculation liquid stream from said separationapparatus means; a fresh water conduit means for providing a source offresh water; and eductor means for combining said recirculation liquidstream and said source of fresh water, arranged such that said source offresh water acts as a motivating force for entraining said recirculationliquid stream within said eductor means, said eductor means being influid flow communication with said conduit means for injecting saidwater stream into said water rings of said vacuum pump.
 2. The vacuumassembly as defined in claim 1 wherein said separation apparatus meansincludes means to separate particulates from said gas-liquid stream toprovide a particulate free recirculation stream.
 3. The vacuum assemblyas defined in claim 1 and further including valve means in said freshwater conduit for providing all water requirements needed by said waterrings in operation of said vacuum pump by said fresh water source,alone.
 4. The vacuum assembly as defined in claim 3 and furtherincluding valve means in said fresh water conduit to control fluidpressure of said fresh water source.